The present invention relates to improvements in methods of thermally transferring decorative films onto objects of various types.
As is known, decorations, images, and texts can be applied to objects of various types from an appropriately printed flexible strip by means of thermal transfer methods, which provide for applying to a wide range of articles of different materials (rubber, plastic, leather, metal, etc.) graphics which serve both as decoration and as a xe2x80x9clabelxe2x80x9d indicating the product or maker.
The images and/or texts in the graphic to be applied to the objects are screen printed on a backing strip, typically made of polyester; and each frame used carries a given number of graphics, which are transferred to the backing strip to obtain, on the strip, a succession of identical (or at least periodically repeated) graphics.
The problem arises, however, of assigning to each graphic constituting each label, and which is the same for all the objects, a code identifying the individual object, e.g. a bar code or progressive number for identifying, by means of the label, the object to which the label is applied. Screen printing obviously fails to provide for achieving this, unless an unreasonable number of different frames is used, which is practically unfeasible.
It is an object of the present invention to provide a method designed to solve the above problem, and which, in particular, is cheap and easy to implement, and provides for forming on a flexible backing strip a decorative thermal-transfer film containing graphics defined by images and/or texts and by a progressive identification code assigned to each graphic.
According to the present invention, there is provided a method of forming on a flexible backing strip a decorative thermal-transfer film containing graphics defined by images and/or texts and by a progressive identification code assigned to each graphic; the method being characterized by comprising: a backing strip processing step, in which a first polymer film is applied to said backing strip; a screen printing step, in which, on said first film, is printed a succession of graphics of images and/or texts which are repeated along said backing strip; a thermographic printing step, in which, on said first film bearing said graphics, a progressive identification code is printed at each graphic; and a finish step, in which a second polymer film is applied on said first film bearing said graphics and associated identification codes, so that said graphics and associated identification codes are interposed and packed between said first and said second film to form said decorative film.
More specifically, said first film is made of a polymer material compatible with the screen printing inks and/or pigments used in said screen printing step, and with the thermographic inks and/or pigments used in said thermographic printing step, so that said screen printing and thermographic inks and/or pigments adhere to said first film.
The graphics can thus be formed cheaply and easily with all the advantages of screen printing, while at the same time assigning a different progressive identification code to each graphic.
The specific sequence of steps and the choice of materials according to the invention provide, not only for high-quality printing of the screen printed images and/or texts and the identification codes, but also for long-lasting results, by preventing delamination or detachment of the codes from the objects to which the graphics are applied. According to the invention, in fact, the graphics and associated identification codes are firmly connected and packed between the two polymer films.